CO2 is a promising and sustainable carbon feedstock for organic synthesis. New catalytic protocols for efficient incorporation of CO2 into organic molecules are continuously reported. However, little progress has been made in the enantioselective conversion of CO2 to form enantioenriched molecules. In order to allow CO2 to become a versatile carbon source in academia, and in the fine chemical and pharmaceutical industries, the development of enantioselective approaches is essential. Here we discuss general strategies for CO2 activation and for generation of enantioenriched molecules, alongside selected examples of reactions involving asymmetric incorporation of CO2. Main product classes considered are carboxylic acids and derivatives (C-2 CO2 bonds), and carbonates, carbamates, and polycarbonates (C-OCO bonds). Similarities to asymmetric hydrogenation are discussed, and some strategies for developing novel enantioselective CO2 reactions are outlined.

Capture of CO2 by amines is an attractive synthetic strategy for the formation of carbamates. Such reactions can be mediated by superbases, such as 1,1,3,3,-tetramethylguanidine (TMG), with previous implications that...

We report herein a straightforward general method for the synthesis of cyclic carbamates from amino alcohols and carbon dioxide in the presence of an external base and a hydroxyl group activating reagent. Utilizing p-toluenesulfonyl chloride (TsCl), the reaction proceeds under mild conditions, and the approach is fully applicable to the preparation of various high value-added 5- and 6-membered rings as well as bicyclic fused ring carbamates. DFT calculations and experimental results indicate a S2-type reaction mechanism with high regio-, chemo-, and stereoselectivity.

2-Oxazolidinones are saturated heterocyclic compounds, which are highly attractive targets in modern drug design. Herein, we describe an ew,s ingle-step approach to 3,4-disubstituted 2-oxazolidinones by aza-Michael addition using CO 2 as ac arbonyl source and 1,1,3,3tetramethylguanidine (TMG) as ac atalyst. The modular reaction, whicho ccurs between a g-brominated Michael acceptor,C O 2 and an arylamine, aliphatic amine or phenylhydrazine, is performedu nder mild conditions. The regiospecific reaction displays good yields (av.7 5%)a nd excellent functional-group compatibility. In addition, late-stage functionalization of drug and drug-like molecules is demonstrated. The experimental results suggest am echanism consisting of severale lementary steps:T MG-assistedc arboxylation of aniline;g eneration of an O-alkyl carbamate; and the final ring-forming step through an intramolecular aza-Michaela ddition.

Herein we report a unique method for preparing diaryl hydroxyl dicarboxylic acids in a diastereospecific manner. The three-component reaction occurs between amino acid, aromatic aldehyde, and primary alcohol in alkaline solutions under microwave-assisted conditions. The dicarboxylic acids are isolated as sodium salts in high yields (up to 77%) by direct precipitation from the reaction solution. The experimental results suggest that the diastereospecificity originates from a [3,3]-sigmatropic rearrangement followed by a sodium-assisted hydride transfer. As further shown, the previously unreported dicarboxylic acids are easily turned into corresponding δ-lactones.